Portable set top box



FIG. 1 is the front view of one embodiment of the portable set top box incorporating my design;

FIG. 2 is a left side view thereof;

FIG. 3 is an isometric view thereof;

FIG. 4 is a back view thereof;

FIG. 5 is a bottom view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a right side view thereof.

A design for a portable set top box is shown in FIGS. 1-7. Any broken lines shown form no part of the claimed design. 

CLAIM The ornamental design for a portable set top box, substantially as shown. 